Document handling apparatus

ABSTRACT

In a document feeding apparatus which separates an edge of a document from a stack prior to feeding the separated document, a document thickness sensing device is employed to detect whether more than one document edge has been separated or whether there has been a failure to separate an edge. The sensing device consists of a finger which is moved over the separated part of a document as it lies on a reference surface. The finger carries a magnetic insert which is magnetically coupled to an inductor so that the displacement of the finger alters the inductance of the inductor.

United States Patent 1191 Derc DOCUMENT HANDLING APPARATUS Roman Derc, Letchworth, England International Computers Limited, London, England Sept. 3, 1970 Inventor:

Assignee:

Filed:

Appl. No.:

[30] Foreign Application Priority Data U.S. Cl. ..27l/57, 192/127, 270/56 Int. Cl. ..B65h 7/12 Field of Search .....271/57, 47; 270/56; 192/127; 33/147 L, 147 N References Cited UNITED STATES PATENTS 1/1954 Dunipacc et al ..33/147 N 11/1959 Arlin ..33/147 N 4/1966 Thompson ..271/57 X Primary Examiner-Even C. Blunk Assistant Examiner-Bruce H. Stoner, Jr. Att0meyK'eith Misegades and George R. Douglas, Jr.

[57] ABSTRACT In a document feeding apparatus which separates an edge of a document from a stack prior to feeding the separated document, a document thickness sensing device is employed to detect whether more than one document edge has been separated or whether there has been a failure to separate an edge. The sensing device consists of a finger which is moved over the separated part of a document as it lies on a reference surface. The finger carries-a magnetic insert which is magnetically coupled to an inductor so that the displacement of the finger alters the inductance of the inductor.

F iii) C ONTROL PAIENIEDJAHBD I975 3. 7 l 3, 646 SHEET 1 or 2 SUC'HDN SOURCE INVENTOR ATTORNEY PATENTEUJAHBO I975 3.713.646

SHEET 2 OF 2 (0 21 I E; 0% a L 5 o L N r0 IO :3 0 2mm a L ATTORNEY INVENTOR DOCUMENT HANDLING APPARATUS BACKGROUND OF THE INVENTION This invention relates to document handling apparatus and in particular to arrangements for detecting incorrect operation of the apparatus.

It has previously been proposed to detect document feeding failures in document handling apparatus by the provision of limit switches such as micro-switches. In this case it has been proposed to provide a first switch having its operating lever spaced less than a single document thickness from a reference face so that this switch is tripped only if at least one document is interposed between the reference face and the switch operating lever. A second switch is positioned with its operating lever spaced at a distance between one and two document thicknesses from the face so that the second switch is tripped only if more than one document is interposed between the lever and the face.

In the present application only a single sensing lever is provided and the use of somewhat bulky mechanically operated switches is avoided by using an inductor whose inductance is adjusted by the positioning of a single piece of magnetic material carried by the sensing lever. The inductance of the inductor is used to provide an indication of the document thickness between the lever and the reference face.

SUMMARY OF THE INVENTION According to the present invention document handling apparatus has a reference surface on which at least a portion of a document is maintained in engagement, thickness sensing means moveable relative to the surface into a position in which it is spaced from the surface by the document thickness, and a coupling between the sensing means and a circuit element having a variable electrical response characteristic, movement of the sensing means in a direction substantially perpendicular to said reference surface producing a corresponding continuous variation in the electrical response characteristic of the circuit element to detect the thickness of document material on said reference surface.

BRIEF DESCRIPTION OF THE DRAWINGS Apparatus embodying the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic view of part of a document feeding apparatus.

FIG. 2 is a sectional view through the apparatus of FIG. 1.

FIG. 3 is a sectional view of part of the apparatus of FIG. 2 shown in a different part of an operating cycle.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, document feeding apparatus includes a table 2 arranged to support a stack 1 of documents. The document stack 1 is arranged on the table 2 with the leading edges of the documents aligned against a front wall 3. A vacuum feed drum is positioned with its periphery slightly below the upper surface of the table 2. The leading edges of the documents in the stack I extend beyond the table 2 and therefore are not supported by the table 2. However, in a static condition of the feeding apparatus the leading edges of the documents are supported by a knife 5 and a suction shoe 6 so that the lowermost document is maintained spaced from the periphery of the feed drum 4.

The suction shoe 6 is formed with a concave depression 25 in its upper surface and a duct 7 extending through the shoe connects through a number of apertures 26 with the concave upper surface. The shoe 6 is mounted on an arm 8 pivoted about a shaft 9. The arm 8 is urged in an anti-clockwise direction by a spring 10 so that the depression 25 in the shoe 6 normally underlies and is spaced away from, the leading edge of the lowermost document of the stack. The shoe 6 may be retracted to a position clear of the leading edge of the document by operation of an electromagnet 11, which attracts a bar 12 of magnetic material carried on the arm and causes the arm 8 to pivot in a clockwise direction about the shaft 9. Similarly, the knife 5 is mounted on a further arm 13 pivoted about the shaft 9. The arm 13 is urged in an anti-clockwise direction by a spring 14 so that the knife 5 normally lies over the concave surface of the shoe 6 and under the leading edge of the lowermost document of the stack 1. The knife 5 may be retracted to a position clear of the leading edge of the document by operation of an electro-magnet 15 which attracts a bar 16 of magnetic material carried on the arm 13 and causes the arm 13 to pivot in a clockwise direction about the shaft 9. A suction source 38 is connected through a flexible pipe 17 to the duct 7 of the shoe 6 and is also connected to the interior of the drum 4. A plurality of apertures 28 in the circumferential wall of the drum 4 connect the interior of the drum with the grooves.

As will be described in detail hereafter, the leading edge of a document to be fed is allowed to be attracted towards the outer surface of the drum 4 and the suction applied to the interior of the drum 4 is then effective to produce, through the apertures 28 and grooves 27, sufficient frictional engagement to feed the document as the drum 4 is rotated in the direction of arrow 29(FIG. 2). Document guides 30 are provided around the drum and an out feed bed 18 is also provided at a point beneath the drum 4 extending tangentially away from the drum surface. A baffle plate 39 is provided within the drum 4 opposite the bed 18, so that the suction feeding force is broken at this point to enable documents fed by the drum to leave its surface. Pinch rollers 19 are also provided at the entrance to the bed 18 and these rollers have conventional resilient surfaces to provide frictional engagement of documents with the drum surface at this point. It will be realized that conventional feeding means such as pairs of feed rollers are provided in association with the bed 18 to carry the documents away from the drum 4.

In order to feed documents sequentially from the lowermost end of the stack 1 the apparatus is operated in the following manner. The electro-magnet 15 is operated to retract the knife 5, thereby permitting the leading edge of the lowermost document to be moved by suction into substantial engagement with the upper surface of the depression 25 in the shoe 6. Due to the concave form of this depression 25 this lowermost document is partially deformed at its leading edge, thus tending to ensure that the separation from the stack 1 is confined to only a single document. The electro-magnet is then de-energized and the spring 14 causes the knife 5 to return to its normal position so that it enters between the now deformed and separated portion of the leading edge of the lowermost document and the remainder of the stack. Thus, at this stage of the operation of the apparatus, a portion of the leading edge of the lowermost document of the stack is separated from the remainder of the documents in the stack 1 by the knife 5 and is held in a position spaced from the vacuum drum 4 by the shoe 6.

1n the present apparatus it is preferred that the feeding of documents is regulated on an on demand basis and a demand signal is generated by conventional control circuitry (not shown) in the event that a document is required to be fed. On receipt of this demand signal the shoe 6 is retracted, leaving the leading edge of the lowermost document unsupported, so that the vacuum drum 4 is now effective to attract the document into frictional engagement with the peripheral surface of the drum by differential air pressure in the conventional manner. Rotation of the drum by conventional means (not shown) in the direction of arrow 29 (FIG. 2) is then effective to cause the lowermost document to be drawn from beneath the remainder of the stack and fed around the drum to the feed bed 18.

Under some circumstances, particularly when thicker documents are to be fed, it may be found that when the leading edge of the document is in engagement with the drum the tractive force obtained by the vacuum acting on this relatively small part of the document may be insufficient to overcome the static frictional forces due to the weight of the remainder of the documents acting on that part of the lowermost document which is supported by the table 2. Under such circumstances, or in order to ensure that under all normal operating conditions there is sufficient tractive force at this stage of feeding of the document, additional pinch rolls may be provided immediately down stream of the shoe 6. Preferably these additional pinch rolls are made selectively positionable at retracted and operative positions. Thus, in the retracted position these pinch rolls are spaced away from the vacuum drum 4 so that the leading edge of the document is not obstructed during its movement into engagement with the surface of the drum 4. When the leading edge of the document engages the vacuum drum 4 the pinch rolls are then moved into their operative position in which they are resiliently urged toward the drum to cause more positive engagement between the drum and the document.

It will also be appreciated that when employed in an on demand" mode of operation the drive to the drum 4 preferably includes a clutch mechanism whereby the drum is rotated intermittently. Hence, the drive would normally be disengaged and the drum stationary. When the demand signal, referred to earlier for initiating feeding of the document, is received, not only is the shoe 6 retracted to release the document leading edge, but the drive to the drum 4 is engaged after the leading edge of the document has moved into engagement with the drum surface. This method of control of movement of the drum 4 has the advantage that accurate timing of the document in relation to other utilizing apparatus is improved.

The knife 5 and its supporting arm structure 13 are arranged, as best shown in FIG. 3, to carry a single document sensing device. The sensing device includes a sensing finger 20 mounted on a pivot 21 on the arm 13; The knife 5 is a hollow shell so that the finger 20 is accommodated within the underside of this shell. The finger 20 has, at the end remote from the pivot 21, a sensing surface with an angle 22 co-acting with the upper surface of the depression 25. A spring 31 urges the edge 22 against the shoe 6. Thus, after a document edge has been attracted into engagement with the concave surface of the shoe 6 with the knife 5 retracted, movement of the knife 5 into its normal position causes the edge 22 to slide over the upper surface of the separated document and it will be clear that edge 22 will be separated from the surface of the depression 25 by a distance equal to the total thickness of documents separated from the stack and retained on the shoe 6. The finer 20 carries a block 23 of ferrite. An inductor 24 consisting of a coil 32 wound on a E-shaped core 33 is supported in a fixed position above the ferrite block 23 on an extension 34 of the knife structure 5 so that the ferrite block 23 is opposite the ends of the limbs of the core 33. it will be realized that the magnitudeof the inductance of the inductor 24 is determined by the length of air gap between the block 23 and the remainder of the magnetic core and the length of the air gap is determined by the position of the edge 22 of the finger 20 and hence by the thickness of document retained by the shoe 6. The inductor 24 is connected to a feed control circuit arrangement 34 by leads 34 from the coil 32. The control arrangement 34 includes an oscillator which is controlled by the variation of inductance to indicate the thickness of the separated document.

The arrangement 34 also includes circuitry for the control of magnets 11 and 15 respectively over lines 36 and 37 and the circuits are arranged so that in operation the knife 5 is retracted from the position shown in FIG. 2. by energization of the magnet 15 over line 37. The leading edge of the document is then allowed to move onto the upper surface of the depression 25 of the suction shoe 6 and the magnet 15 is de-energized to allow the knife 5 to move back over the now separated document edge. As the knife 5 moves back to its original position the tip 22 of the finger 20 is moved by the document and displaces the block 23. The output of the oscillator is examined at this point to determine whether a single document has been attracted or whether no documents or more than one document has been attracted. If a single document indication is obtained the remainder of the document feeding operation is permitted to take place and the magnet 11 is energized over the line 36 to withdraw the suction shoe 6 from the document edge. However, if a signal indicating that more than one document has been separated is obtained, the knife 5 is once more retracted and returned to its normal position again in an attempt to separate a single document from the stack. This operation may be repeated a number of times after which a signal indicating the need for intervention of an operator is generated.

The sensing device as described is incorporated in an apparatus for selecting single documents to be fed in turn from the stack and in conjunction with the apparatus described the sensing device enables a check to be made to determine whether correct separation has been effective prior to any feeding of the document away from the stack. Thus, used in this way the device not only permits further attempts to be made automatically by the apparatus to separate a single document but also if operation intervention becomes necessary the document which has caused mal-operation of the separator is easily identified and removed from the apparatus since it is still in the stack of documents on the table 2.

It will also be apparent that the sensing device may also be used in conjunction with other document handling apparatus; for example, document feeds of different kinds to that described. Thus, the sensing device consists essentially of a reference surface over which documents are required to pass, or upon which they may be laid, together with a finger or probe which is displaced away from the reference surface by the documents whose thickness is to be measured. The degree of displacement by mechanical linkage is caused to produce a corresponding variation in the spacing of a magnetic member, like the ferrite block 23, with respect to an inductor, such as the inductor 24. The variation in inductance of the inductor thereby produced may be used in conjunction with conventional circuitry to produce signals indicative either of the actual document thickness or of the departure of the measure thickness from a predetermined acceptable tolerance.

lclaim:

1. Document handling apparatus including a reference surface; means to maintain document material in engagement with said surface; thickness sensing means movable relative to said surface into a position in which it is spaced from the surface by the thickness of document material engaged therewith; a circuit element having a variable electrical response characteristic; and coupling means between the circuit element and the sensing means arranged to produce, in response to movement of the sensing means in a direction substantially perpendicular to said reference surface a corresponding continuous variation in said response characteristic to detect the thickness of said document material; in which the sensing means includes a carrier; means for moving the carrier in a direction substantially parallel to said reference surface; a sensing finger supported in said carrier for movement in a direction substantially perpendicular to said reference surface, the sensing finger being moved along said reference surface by movement of said carrier and being displaced from said surface by document material engaged thereon; and in which the circuit element consists of an inductor supported on said carrier and magnetically coupled to said sensing finger, whereby movement of said sensing finger in said perpendicular direction produces a variation in the effective inductance of said inductor.

2. Document handling apparatus as claimed in claim 1, in which said inductor includes an open-ended magnetic structure and a coil wound on said structure, and in which the finger carries a magnetic member positioned adjacent the open ends of said magnetic structure.

3. Document handling apparatus as claimed in claim 2, including circuit means connected to said coil, the

cjrcuit means bein arranged to produce an output signal if the mduc ance 0 said inductor is set to a predetermined magnitude in response to the positioning of the sensing finger at a distance from the reference surface corresponding to a single document thickness.

4. Document handling apparatus as claimed in claim 3, including means for supporting a stack of documents; separator means positioned adjacent an end face of a document stack supported by the supporting means, the separator means having said reference surface spaced away from said end face; means effective to cause an edge of a document at said end face to be separated from the stack and moved into a position with a least part of said edge engaged against said reference surface, the carrier moving means being effective to move said carrier into the separation between the engaged part of the edge and the remainder of the stack to cause said sensing finger to ride over the engaged edge. 

1. Document handling apparatus including a reference surface; meanS to maintain document material in engagement with said surface; thickness sensing means movable relative to said surface into a position in which it is spaced from the surface by the thickness of document material engaged therewith; a circuit element having a variable electrical response characteristic; and coupling means between the circuit element and the sensing means arranged to produce, in response to movement of the sensing means in a direction substantially perpendicular to said reference surface a corresponding continuous variation in said response characteristic to detect the thickness of said document material; in which the sensing means includes a carrier; means for moving the carrier in a direction substantially parallel to said reference surface; a sensing finger supported in said carrier for movement in a direction substantially perpendicular to said reference surface, the sensing finger being moved along said reference surface by movement of said carrier and being displaced from said surface by document material engaged thereon; and in which the circuit element consists of an inductor supported on said carrier and magnetically coupled to said sensing finger, whereby movement of said sensing finger in said perpendicular direction produces a variation in the effective inductance of said inductor.
 1. Document handling apparatus including a reference surface; meanS to maintain document material in engagement with said surface; thickness sensing means movable relative to said surface into a position in which it is spaced from the surface by the thickness of document material engaged therewith; a circuit element having a variable electrical response characteristic; and coupling means between the circuit element and the sensing means arranged to produce, in response to movement of the sensing means in a direction substantially perpendicular to said reference surface a corresponding continuous variation in said response characteristic to detect the thickness of said document material; in which the sensing means includes a carrier; means for moving the carrier in a direction substantially parallel to said reference surface; a sensing finger supported in said carrier for movement in a direction substantially perpendicular to said reference surface, the sensing finger being moved along said reference surface by movement of said carrier and being displaced from said surface by document material engaged thereon; and in which the circuit element consists of an inductor supported on said carrier and magnetically coupled to said sensing finger, whereby movement of said sensing finger in said perpendicular direction produces a variation in the effective inductance of said inductor.
 2. Document handling apparatus as claimed in claim 1, in which said inductor includes an open-ended magnetic structure and a coil wound on said structure, and in which the finger carries a magnetic member positioned adjacent the open ends of said magnetic structure.
 3. Document handling apparatus as claimed in claim 2, including circuit means connected to said coil, the circuit means being arranged to produce an output signal if the inductance of said inductor is set to a predetermined magnitude in response to the positioning of the sensing finger at a distance from the reference surface corresponding to a single document thickness. 